garrett376

I think this is probably a question only Adrian may know... but I'd thought I'd try the masses!

I was reading Adrian's book and saw the note that the 993 DME relay should be used instead of the original equipment 944 version when replacing the relay. Today I bought a relay for a backup to carry with the car, and decided to remove the older, functioning 944 version to use as my backup, and install use the new 933 DME/fuel relay.

My question: is the 993 relay better in any way? The wording in Adrian's book suggests it is... how so? I figured I could not go wrong installing the newer version and using the older relay as my backup instead...

Thanks for again satisfying my 964 curiosity!!



For those in the snow, here's winter at the beach...

Lorenfb

They're all the same, i.e. they become intermittent because of bad solder joints
as they vibrate in the relay socket. So, always carry a spare.

Have Fun
Loren
'88 3.2

viperbob

The newer relays with 993 part #s have been much less prone to failure. Do a search on the 993 board for more specific electrical info.

They are still not perfect, and do still fail. You should ALWAYS carry a spare.

Ruairidh

The 993 relay P/N being 993 615 227 00 (per Adrian's excellent book).

What is the ballpark price for these?

By the way ViperBob, nice to see you frequenting this board recently - I've long wished I was in SoCal for one of your weekend surgery sessions (w/BBQ and beer).

garrett376

I bought the relay for $18 with Porsche Club discount at the local Porsche dealer. Not bad!!

Adrian

The 993 DME/Fuel pump relay is an improved version. Not perfect but the contacts are slightly meatier and the problems of the 944 unit were in the main rectified.
However they are still electro-mechanical devices and will eventually fail because they are energised the entire time when the engine is running and have quite a current flow through the fuel pump contacts.
The relays do not vibrate in the central electric.
Ciao,
Adrian
964C4

PS: For the record I have never carried a spare and to be quite honest do not intend to.

Rdelvalle

I am having starting problems. After my Sunday drive last week I stopped the car and it would not start. Later that night I pushed it into my drive way and it then started. I have started it everyday last week. Today I started and it ran for a few minute then it just quit. It will crank but not start. Tonight I tried again it started. The tank is full of premium gas. I did check and the DME relay is the 944 version probably the original fatory one. I am the third owner of this car.

Of course the DME is the number one suspect, but could it be the fuel pump or other sensor? I will chanege the DME relay any way after reading all of the coments but if it is not that I risk being stranded. If you hook up the diagnostics computer would it tell you what could be wrong?

________________________________________________________
1997 993, 39.8k mi

1990-964

What you are describing is exactly what happened when my fuel pump failed. My first thought was the DME relay. The starter would crank but no ignition. In the past when the relay failed it was very similar. Replaced pump a year and a half ago and not a problem since.

Rdelvalle

Thank you 1990-964: I did change the DME but I have not driven the toy since the change, it is resting in the garage. My mechanic was able to get a reading when the car failed to start and the computer stated that it was the DME relay open circuit. He thinks it was the relay. I had the mechanic do the work so he could check with the the computer and get a diagnosis otherwise I would have changed the DME myself. I hope he is right and it is not the fuel pump I am terrified of being stranded and having to flat bed the p-car.

Did you change the DME and then relized that it was the fuel pump?
______________________________________________
1997 993, 39.8k mi, Arctic Silver